The present invention relates to a padded elements for vehicles and to methods of manufacturing them.
More particularly, the invention relates to a padded element for a vehicle, the element comprising flexible synthetic foam padding supporting at least one flexible member that is less flexible than the foam and that presents a support face for a user to bear against, said support face being covered by a flexible outer decorative covering, and a flexible lining being interposed between the flexible member and the outer decorative covering.
Way of non-limiting example, the flexible member under consideration herein can be constituted in particular by:
one or more plies of electric wires constituting in particular a sensor (to sense the presence of a user, to measure the weight of the user, etc.), an electric ply for heating, etc.;
one or more semirigid sheets of plastics material or the like containing or supporting such plies of wires or containing other types of electrical component, etc.
Document DE-A-196 01 969 describes an example of such a seat element, in which the flexible lining is constituted by a layer of foam forming part of the padding, the flexible member being embedded in the foam of the padding while the foam is polymerizing in a mold.
Nevertheless that technique does not present a sufficient guarantee that the layer of foam will be formed completely between the flexible member and the outer decorative covering, insofar as there is a major risk of the foam polymerizing before it fills the space that extends between the bottom of the mold and said flexible member. Under such circumstances, the above-mentioned flexible lining is incomplete, thereby degrading the comfort of the seat element since the occupant of the seat can then feel the presence of the flexible member under the decorative covering. In addition, localized gaps in the foam produce points of weakness in the padding which lead to accelerated degradation of the padding over time, and thus to a shorter lifetime for the seat element.
A particular object of the present invention is to mitigate those drawbacks.
To this end, according to the invention, a seat element of the kind in question is characterized in that the lining is less than 20 millimeters (mm) thick and comprises superposed layers of flexible materials that are distinct from the foam constituting the padding, the flexible lining comprising at least:
a film adapted to constitute a barrier against the synthetic foam prior to its polymerization, said film adhering to the synthetic foam; and
at least a first compressible flexible layer covering the film on the opposite side to the padding and adhering to said film, the first flexible layer presenting:
permeability to air that is less than 200 liters per square meter per second (l.mxe2x88x922.sxe2x88x921) under a pressure difference of 100 pascals (Pa);
load-bearing capacity lying in the range 3 kPa to 12 kPa; and
thickness lying in the range 1 mm to 10 mm.
By means of these dispositions, good comfort is ensured for the user who bears against the support face of the padding.
In preferred embodiments of the invention, use may optionally also be made of one or more of the following dispositions:
the padding is made of polyurethane foam and the film comprises firstly a main component selected from polysaccharides and animal proteins, and secondly a plasticizing agent selected from: caprolactone, polylactic acid, cellophane, paper, polyethylene, and isocyanate;
the first flexible layer is made of a material selected from synthetic foams and non-woven fabrics;
the flexible lining further comprises a second compressible flexible layer interposed between the first flexible layer and the outer decorative covering, said second flexible layer adhering to said decorative covering and presenting:
thickness lying in the range 1 mm to 6 mm; and
load-bearing capacity lying in the range 5 kPa to 20 kPa;
the second flexible layer is made of a material selected from synthetic foams and non-woven fabrics;
the second flexible layer adheres to the first flexible layer;
the flexible member adheres to the film;
the outer decorative covering forms at least one reentrant line which penetrates into the padding, said padding supporting at least two flexible members adhering to the film of the flexible lining, said flexible members being placed on either side of the reentrant line and being interconnected via at least one flexible strap which forms a loop extending towards the inside of the padding away from the reentrant line formed by the outer decorative covering (in this embodiment, the adhesion of the flexible members on the flexible lining film guarantees that the strap in the form of a U-shaped loop is properly positioned before the padding is molded);
the strap is spaced apart from the reentrant line of the outer decorative covering by the padding having a thickness of not less than 55 mm;
the flexible lining and the outer decorative covering form a laminate having a total thickness of not more than 8 mm; and
the padded element constitutes a seat element.
The invention also provides a method of manufacturing a padded element as defined above, the method comprising the following steps:
a) at least one flexible lining is placed in a mold defining a bottom cavity, the film being placed towards said cavity and the flexible member adhering to the film;
b) suction is established in the mold pressing said flexible lining against the mold;
c) flexible synthetic foam in the still unpolymerized state is cast into the mold cavity against the film of the flexible lining; and
d) the synthetic foam is allowed to polymerize.
Advantageously, during step a), a laminate is placed in the mold, the laminate comprising both the flexible padding and the outer decorative covering.